Case report
In the case report, we present a case of a 13-year-old patient with chronic debilitating fatigue who meets the criteria for CFS/ME. The patient was examined in detail by a paediatrician (anamnestic unclear cause, resting tachycardia in the physical examination, laboratory tests within normal limits), endocrinologist (normal hormonal profile for a given age, Tanner stage 3), infectologist (serology for typical viruses negative), psychologist (normal cognitive functions). For a history of resting tachycardia, the patient was examined by a cardiologist where no cardiogenic cause of fatigue was demonstrated, sinus tachycardia was present, and the patient was recommended head-up-tilt test, which showed the presence of postural orthostatic tachycardia. Due to the idiopathic nature of the difficulties and the excluded secondary cause, a two-day protocol examination by cardiopulmonary exercise testing was indicated. Written consent was taken and documented. Before the examination, resting spirometry (physiological findings) was performed, resting ECG (sinus tachycardia) and a shortened Schellong test with a tachycardic response to orthostasis immediately after standing up and after 3 minutes of standing. Subsequently, standard CPET using a treadmill (Itam, Poland) with individualized protocol with progressive increase in workload until exhaustion and breath-by-breath analysis of exhaled gases (Geratherm, Germany) was performed. On the first day, basal values were determined, the patient subjectively tolerated the examination well, the exercise ended prematurely due to subjective fatigue and a feeling of lack of air. On the second day, under the same conditions, CPET was repeated, during which the patient also terminated the exercise prematurely, but a half minute later than on the first day. Using this methodology, the patient did not meet the diagnostic criteria for PEM and subsequently CFS/ME (decrease in monitored values on the second day of examination) (table 1). On both days, during exercise, a bizarre pattern of respiration with malposition of the respiratory act to the large airways was observed by observing the flow-volume loop. An analysis of the respiratory pattern identified an erratic respiratory pattern (figure 1a) with low resting ETCO2 (table 1) and tachypnoea at maximal workload with dominant ventilation of dead space (figure 1b, 1c). The consequence of this pattern of respiration is a chronic state of hypocapnia and respiratory alkalosis, which is metabolically compensated in the patient. Fatigue and increased heart rate are expected clinical manifestations. Respiratory rehabilitation was recommended to the patient in order to fixate the correct breathing patterns (diaphragmatic breathing) and psychological guidance. The patient was subsequently retested 3 months after the start of physiotherapy and psychotherapy at the request of the parents. Retesting showed significant improvements in the monitored parameters (table 1) as well as in the clinical condition of the patient. The patient’s overall fitness increased, an adequate resting respiratory pattern was present (figure 1d), ventilatory efficiency was adjusted (VE/VCO2 in table 1, figure 1f), and the patient reported a subjective increase in energy. Prior to the examination, we performed a Schellong test on the patient, in which there were no signs of postural orthostatic tachycardia.